Purpose: We describe an increase in the number of US Listeriosis outbreaks associated with produce.
Methods: We queried CDC’s Foodborne Disease Outbreak Surveillance System (FDOSS), reviewed published reports, and unpublished CDC data for all Listeriosis outbreaks associated with produce during 1973–2014. We analyzed the number of outbreaks, outcomes (hospitalizations and deaths), and implicated produce items. We considered cases in pregnant women or infants ≤ 28 days old to be pregnancy-associated. Factors contributing to these outbreaks were reviewed.
Results: During 1973–2014, six Listeriosis outbreaks associated with produce were detected in the United States. All six outbreaks occurred after 2008 and involved domestically grown produce. These outbreaks included 216 illnesses (range 2–147, median 15 per outbreak), 207 hospitalizations, 47 deaths, and two fetal losses. Twenty-one illnesses (10%) were pregnancy-associated. These comprised 21% of Listeriosis outbreaks and 59% of Listeriosis outbreak-associated illnesses after 2008. Two outbreaks were associated with sprouts and one each with cantaloupe, caramel apples, celery, and stone fruit. Environmental assessments indicated that structural defects, inadequate produce handling and cleaning techniques, and inadequate facility and equipment design were possible sources of contamination.
Significance: No US Listeriosis outbreaks were linked to produce in the first 25 years of US foodborne Listeriosis outbreak surveillance compared with six outbreaks after 2008. Both vegetables and fruit were implicated. Reasons for the emergence of produce-associated Listeriosis outbreaks are not known. However, improvements in the detection and investigation of outbreaks might have contributed to the identification of previously unrecognized sources. Manufacturers, growers, and packers should implement measures to minimize contamination.